Sewer backing up during a storm: what's normal, what's not, and when to call.

Sewage backing up right now? Stop all water use, keep everyone away from the area, and call us at (949) 328-6002. We answer around the clock, and we'll walk you through the next steps while our team heads your way.

It's been raining hard for hours, and now something inside the house is off. Water is coming up through the shower drain, or the toilet won't stop rising. Maybe there's a dark puddle forming around the floor drain in the garage. Maybe there's a smell before you see anything at all. And the first question is the right one: is this just the storm, or is something wrong with my sewer line?

It's unsettling. We get it. We've walked into hundreds of homes where this is happening, and the homeowners are standing there not sure what to do first. That's exactly why we put this together: how to tell what's normal during a storm and what's not, and then the step-by-step for the first hour, in order, so you don't have to think it through in the moment.

Is it the storm, or is it your sewer line?

Here's the thing about rain and sewer lines: they're supposed to be strangers. Your home's sanitary sewer line, the one your toilets, showers, and sinks drain into, is a sealed system, kept separate from the storm drains that handle rain. California plumbing code keeps them apart on purpose. So when a storm has your drains acting up inside the house, the rain isn't the cause. It's the messenger.

What's normal during a heavy storm: puddles in the yard, gutters running over for a stretch, a patio or yard drain moving slowly while the sky is dumping. Outside drainage takes a beating in a real storm, and most of it recovers on its own once the rain lets up.

What's not normal: water rising in a shower or tub drain, a toilet bubbling or rising when nobody flushed, a sewage smell from floor drains, or more than one fixture running slow at once. Those are main-line signs. If stormwater is finding its way into your sewer line, it's getting in through cracks, root intrusion, or joints that have shifted open. The line already had a problem. The storm just found it.

One early-warning spot worth knowing: the garage floor drain is usually the lowest drain inside the house, so it's often the first place a backup shows itself. If yours is backing up or smells like sewage during a storm, treat it as a main-line sign, not a garage problem. Our garage drain guide covers how that drain connects to the rest of the system.

Our own job records back this up. Across 5,500+ drain and sewer calls since 2020, storm and yard drain work spikes in September and again in November, right around the first storms of the season. Interior sewer backups, though, happen year-round. Rain doesn't create a blockage. It reveals one that was already building.

Geography plays a part too. In Laguna Beach, drain and sewer work makes up 21.5% of everything we do, nearly double our norm, and almost 4 in 10 of our drain customers there have had a problem come back at least once. Many of the homes there have been standing for decades, and the lines under them have been working just as long. A related story runs the length of the Aliso Creek corridor: much of south county's storm runoff channels through Lake Forest, Laguna Hills, Aliso Viejo, and Laguna Niguel on its way to the ocean at Laguna Beach, so when a big storm arrives, the water along that stretch moves with real volume.

If a storm is in the forecast and nothing is backing up yet, the better read is our rainy-season drain and sewer readiness guide, along with our look at what this winter's El Niño forecast means for Orange County homes. The rest of this page is for the moment when it's already happening.

The first 10 minutes: stop the water.

This is the most important window. Everything you do right now is about preventing the situation from getting worse.

Step 1: Stop all water use immediately. No flushing. No sinks. No laundry. No dishwasher. Every gallon of water you send down a drain has nowhere to go, so it comes back up. Walk through the house and tell everyone. If someone is in the shower, they need to turn it off. If the washing machine is running, stop the cycle.

Step 2: Keep kids and pets away. A sewage backup in your home is not just dirty water. It's raw sewage, and it carries things you do not want anyone touching. We'll talk more about that in a moment. For now, keep everyone out of the affected area. Close the door if you can.

Step 3: Check your electrical outlets. If sewage has reached any electrical outlets, power strips, or appliances sitting on the floor, go to your breaker panel and turn off power to the affected areas. Water and electricity are a serious combination. If you're not sure which breakers control which rooms, turn off the main breaker until a professional arrives.

Step 4: Call a plumber. When you call, say "I have a sewage backup in my home." Those words tell us this is a priority call, not a slow drain or a dripping faucet. A sewer backup involves health hazards and active damage, so it goes to the front of the line. If you're in Orange County, our emergency line is (949) 328-6002. We respond to emergency plumbing calls around the clock.

Is your sewer backing up right now? Stop all water use, keep everyone away from the area, and call us at (949) 328-6002. We'll walk you through next steps on the phone while our team heads your way. Contact us here if you prefer to reach out online.

While you wait for the plumber (10-60 minutes).

The plumber is on the way. Here's how to use this time well.

Document the damage. Pull out your phone and take photos and video of everything. The standing water, the affected flooring, any items that have been touched by sewage, the fixtures where water came up. Get timestamps. Get wide shots of the room and close-ups of the damage. Your insurance adjuster will want to see what it looked like before cleanup started, and this evidence is much harder to recreate after the fact.

Contain the spread if you can do it safely. If the sewage is creeping toward a carpeted room or a hallway, old towels or plastic sheeting can slow it down. Don't wade through it in bare feet or flip-flops. Rubber boots or at minimum thick-soled shoes you can throw away afterward. The goal isn't to clean anything up yet. It's just to limit how far it travels.

Open windows for ventilation. Sewer gas contains hydrogen sulfide and methane. Neither is something you want building up in an enclosed space. Open windows in and near the affected area. If you have a box fan, point it toward an open window to move air out of the house. Fresh air makes a real difference while you wait.

Do not start cleanup yet. This is counterintuitive. Everything in you wants to start mopping and scrubbing. But cleaning up before the line is cleared is like bailing water out of a boat that still has a hole in it. The backup has to be resolved first. Once the plumber clears the line and confirms it's flowing, then cleanup can begin properly.

What NOT to do during a sewer backup.

When something this stressful happens, instinct kicks in. Some of those instincts will make the situation worse. Here's what to avoid.

Don't flush again hoping it clears. We understand the impulse. Maybe it was just a one-time thing, right? It wasn't. Flushing again sends more water into a system that can't move it. Every flush adds to the volume of sewage in your home.

Don't use chemical drain cleaners. They won't clear a main sewer line blockage. The chemicals sit in the standing water, create fumes in an enclosed space, and become a hazard for the plumber who arrives next. Chemical cleaners are designed for minor sink clogs, not a backed-up sewer line.

Don't use a shop vac on raw sewage without proper protection. A shop vac can technically pick up water, but raw sewage aerosolizes when it passes through the vacuum. That puts bacteria and pathogens into the air. Professional remediation teams use equipment designed specifically for contaminated water.

Don't try to snake the main line yourself. The main sewer line is typically a 4-inch pipe that runs from your house to the city connection. Clearing it requires a powered cable machine or hydrojetting equipment. A handheld drain snake from the hardware store won't reach the blockage, and you can damage the pipe or the cleanout fitting trying to force it.

Don't wait it out. A partial backup always becomes a full one. If sewage is coming up through drains, the blockage isn't going to clear itself. The longer you wait, the more water damage, the more contamination, and the harder the cleanup. And if it started during a storm, remember: the rain didn't cause it, so the end of the rain won't fix it.

After the plumber clears the line.

Once the sewer line is flowing again, the immediate emergency is over. Now it's about getting your home back to normal. This part takes longer than most people expect, and it's important to do it right.

Professional cleanup and remediation. Sewage is classified as Category 3 water (also called "black water") by the restoration industry. That's the most contaminated category. Everything it touched needs to be properly sanitized or removed.

Here's the general rule: if it's porous and it touched sewage, it probably has to go. That includes carpet and carpet padding, upholstered furniture, mattresses, drywall (if sewage wicked up into it), cardboard boxes, and paper goods. These materials absorb contaminated water into their fibers, and even industrial sanitizers can't reliably reach all of it.

Hard surfaces can be sanitized. Tile, concrete, vinyl, sealed hardwood, and porcelain can all be properly cleaned and disinfected. A solution of one cup of bleach per gallon of water is the standard for hard surface disinfection after sewage contact. Professional remediation companies will also test to confirm the area is safe.

Run the air. After cleanup, run fans and dehumidifiers in the affected area for at least 48-72 hours. Moisture that stays behind feeds mold growth, and mold can start developing within 24-48 hours in warm, damp conditions. Southern California's mild climate can mask how much moisture is still trapped in subfloor materials.

From the Field

One of the biggest storm floods I've ever seen in person was at a rental in Newport. Very nice neighborhood, very hilly, and this home sat toward the bottom of the street with a driveway that sloped back down toward the house. During one heavy storm the street gutters were clogged, so all the water from the entire street came pouring down the hill and started moving toward the home.

Here's the frustrating part. The property had over 48 drains plus a big French drain in the driveway, all designed to collect that water and send it out the back, down the hill behind the house. But none of it had been serviced in a long time. Roots and debris everywhere. The drains were of no use.

The renter, Sarah, had moved in just a few weeks earlier, and the homeowner was living in another country, so she couldn't get permission to make decisions as fast as she needed to. The home ended up about 4 inches under water, and some very high-end wood floors were destroyed in moments. We brought in a local restoration company we work with to start emergency service as a courtesy until she could reach the homeowner. In the end we replaced the entire drainage system for the property. Regular maintenance would have prevented all of it.

Filing an insurance claim.

This is the part where a lot of homeowners get surprised, so it's worth understanding before you're in the middle of it.

Standard homeowners insurance usually doesn't cover sewer line work. The pipe itself, the clearing, the camera inspection, the repair if the pipe is damaged, that's typically your responsibility. Standard policies consider sewer lines part of your home's infrastructure, similar to your roof or foundation.

Sewage backup damage may be covered if you have the right rider. Look for "sewer backup coverage" or "water backup coverage" on your policy. This is an add-on that covers damage to your home and belongings caused by water or sewage backing up through drains. It's typically $40 to $150 per year depending on coverage limits, and it's one of those things that feels unnecessary right up until the moment you need it.

What your insurer will want. Photos and video from before cleanup started (this is why we said to document everything). The plumber's invoice showing what was found and what was done. Remediation estimates or invoices. A list of damaged items with approximate values. The more organized your documentation, the smoother the process.

Check your policy now, before you need it. If you don't currently have sewer backup coverage, call your insurance agent this week. It's one of the least expensive riders you can add, and it covers one of the messiest situations a homeowner can face.

Preventing it from happening again.

Once a sewer backup is cleared and the cleanup is done, the question becomes: why did this happen, and how do we make sure it doesn't happen again?

Start with a camera inspection. After clearing the line, a good plumber will run a sewer camera inspection to see what caused the blockage. This is the single most important step. The camera shows us whether it was tree roots growing into the pipe, a buildup of grease and debris, a collapsed section, a belly (low spot) in the line where material accumulates, or something that was flushed that shouldn't have been. The cause determines the prevention plan.

Regular maintenance based on what we find. If roots are the issue, scheduled drain cleaning every 12-18 months keeps them from building back up to a full blockage. If grease was the culprit, it's about changing habits in the kitchen. If the pipe itself is damaged, we'll talk about repair or replacement options.

Get ready before the rainy season, not during it. If your backup showed up with a storm, the smartest move is to get ahead of the next one. Our rainy-season drain and sewer readiness guide walks through the pre-season checklist: what to clear, what to inspect, and what to watch when the first big storm rolls in.

Expert Tip

Take a look at where your rain gutters let out. Most gutter downspouts drain right beside the house, which concentrates a lot of water at the foundation in a heavy storm. The best setup is connecting the gutter drain directly to the storm drains in your yard, so the water gets detoured away from the property entirely. If that's not an option, make sure the ground in that area is graded so water moves away from the house, or have a storm drain added nearby. My neighbor across the street, Matt, learned this one the hard way: water collecting at the corner of his house got inside and ruined his wood floors. Our team piped his gutter into the storm drains, and I've checked in after many rains since. The problem never came back. One more note from his situation: aging flashing around the home made things worse, and that's typical. Complications tend to cluster.

Know where your cleanout is. Every home has a main sewer cleanout, usually a capped 4-inch pipe near where the sewer line exits your foundation. It might be in the yard, the garage, or near a crawl space access. Knowing where it is saves valuable time during an emergency because that's where the plumber accesses the line.

Learn the early warning signs. A gurgling toilet is often the first hint that something is developing in the sewer line. Slow drains in multiple fixtures at the same time. A faint sewage smell near floor drains. Water level in the toilet bowl rising or dropping on its own. These signs show up days or weeks before a full backup. Catching them early means a simple clearing instead of an emergency.

For a complete walkthrough of what clogs a sewer line and how to stay ahead of it, our full guide covers the topic in detail.

The bottom line.

A sewer backup is a situation where acting quickly really matters. The steps are simple and they work: stop all water use, keep everyone out of the affected area, call a plumber, and document everything while you wait. And if it arrived with a storm, remember what the rain actually did: it found a problem that was already there.

What you do in that first hour determines whether this is a manageable situation or a much bigger one. And once the line is cleared, the most important conversation you can have with your plumber is about what caused it, because understanding the root cause is how you keep it from happening again.

If you're dealing with a sewer backup right now or you've noticed warning signs that one might be developing, give us a call at (949) 328-6002 or reach out online. We'll take care of it. And if the storms are still ahead of you, our rainy-season readiness guide is the place to start.

*Written by Eric Olson, Licensed Master Plumber, Olson Superior Plumbing, Orange County, CA.*